1. Field of the Invention
The present invention relates to a data recording apparatus and method for writing data to an optical disc, data playback apparatus and method for reading data from an optical disc, and an optical disc.
2. Description of the Related Art
There has become popular a CD (compact disc) system in which an optical disc having an outside diameter of about 120 mm and a thickness of about 1.2 mm is used as a recording medium and a signal is read from, or written to, the optical disc by projecting a light converged by an objective lens onto a signal recording surface of the optical disc.
The CD system has initially been developed as a recording and playback system for digital audio data. As this technology has been accepted very widely, a wide variety of CD systems have so far been proposed for various applications.
Recently, the personal computers have been used as an information processing means in more and more ordinary households. Along with this tendency, a read-only optical disc called xe2x80x9cCD-ROM (read-only memory)xe2x80x9d has become popular to have recorded therein data handled in the personal computer.
Also, a recordable optical disc such as CD-R (recordable) and rewritable optical disc such as CD-RW (rewritable) have been developed and used in practice as optical discs interchangeable with the CD-ROM.
Data is recorded to the CD-R and CD-RW by the so-called xe2x80x9cTrack At Oncexe2x80x9d method by which data is written in units of a track, and the so-called xe2x80x9cPacket Writingxe2x80x9d method by which data is written in units of a packet which is a smaller unit than the track. When either the xe2x80x9cTrack At Oncexe2x80x9d or xe2x80x9cPacket Writingxe2x80x9d method is used to record data to the CD-R or CD-RW, a plurality of data linking blocks is provided between tracks or between packets, each being a unit in which data is continuously recorded, according to a predetermined linking rule. That is, in case data is recorded by the xe2x80x9cTrack At Oncexe2x80x9d method or xe2x80x9cPacket Writingxe2x80x9d method, it will be written with a plurality of data linking blocks appended to each unit of data which is to be continuously written.
The reason why the plurality of data linking blocks is appended between tracks or packets is that the CD-R and CD-RW adopt a convolution type cross coding method called xe2x80x9cCIRC (cross interleaved Reed-Solomon code)xe2x80x9d and a data discontinuity takes place at a linking position because of the CIRC interleaving. That is, the data linking blocks are provided at a linking position of data as a guard area in which data missing is prevented in linking interleaved data to each other.
The amount of data handled in the personal computer has increased more and more, and thus the CD-ROM, CD-R and CD-RW as recording media for recording data have strongly been required to have an increased storage capacity.
To meet such a requirement, the so-called double-density CD-R and CD-RW maintaining the CD format and having a recording density about 2 times higher than the current CD format are under development.
In the double-density CD-R and CD-RW, the EFM modulation and demodulation methods and wobble signal frequency applied to the CD-R and CD-RW having the current format (will be referred to as xe2x80x9cnormal-density CD-Rxe2x80x9d and xe2x80x9cnormal-density CD-RWxe2x80x9d, respectively, hereunder) are not changed but the track pitch is decreased while the linear density is increased, to whereby elevate the recording density up to about double that of the normal-density CD-R and CD-RW.
In the double-density CD-R and CD-RW whose recording density is increased by reducing the track pitch while increasing the linear density, a defect such as scratch to a recording mark will be larger than that in the normal-density CD-R and CD-RW. That is, in the double-density CD-R and CD-RW, the burst error length will be larger than in the normal-density CD-R and CD-RW.
Therefore, the double-density CD-R and CD-RW will be more susceptible to a burst error than the normal-density CD-R and CD-RW. So, proper the CIRC error correcting method used in the current normal-density CD-R and CD-RW is adopted as it is in the double-density CD-R and CD-RW, an error cannot be corrected in some cases, which will highly possibly lead to an improper reading of data.
To positively correct the burst error, it is effective to increase the interleaving length by setting a large delay parameter indicative of a CIRC unit delay. However, with an increased interleaving length, the linking rule adopted in the current normal-density CD-R and CD-RW is not capable of accurately linking data. Therefore, to write data to the double-density CD-R and CD-RW, it is necessary to adopt a suitable linking rule for the double-density CD-R and CD-RW.
Also, the optical disc drive for such a double-density CD-R or CD-RW has to be able to properly write and read data to and from a double-density CD-R or CD-RW and to the normal-density CD-R or CD-RW as well. Namely, the optical disc drive for the double-density CD-R and CD-RW is required to be able to support also the normal-density CD-R and CD-RW, that is, they have to be compatible with the latter also.
It is therefore an object of the present invention to overcome the above-mentioned drawbacks of the prior art by providing a data recording apparatus and method in which a linking rule suitable for use with an optical disc having a high recording density is used to link data, thereby permitting to realize a proper data recording to the optical disc, a data playback apparatus and method which can read an optical disc having data recorded therein according the above-mentioned linking rule, the data recording and playback apparatuses and methods being able to support an optical disc having a current format as well, and an optical disc having recorded therein a program of the above data recording and playback.
The above object can be attained by providing a data recording apparatus for recording data to a conventional standardized optical disc as well as to an optical disc having a higher recording density than the former optical disc, the apparatus including according to the present invention:
means for appending a plurality of data linking blocks to each unit of data going to be continuously written to the optical disc;
means for error-correction coding, including interleaving, of the data in the data unit having the data linking blocks appended thereto by the data linking block appending means;
means for continuously writing the data having been subjected to the error-correction coding by the data-correction coding means to the optical disc at each unit of data having the plurality of data linking bocks appended thereto by the data linking block appending means; and
an optical disc discriminator for judging to which the data is going to be written by the data writing means, the conventional standardized optical disc or the optical disc having a higher recording density than the former optical disc.
In the above data recording apparatus according to the present invention, when the optical disc discriminator has judged that data is going to be written by the data writing means to the conventional standardized optical disc, the data linking block appending means appends a plurality of data linking blocks, including two run-out blocks, to each unit of data going to be continuously written to the optical disc, and the error-correction coding means interleaves the data with a unit delay of four frames. When the optical disc discriminator has judged that the data is going to be written by the data writing means to the optical disc having the higher recording density than the conventional standardized optical disc, the data linking block appending means appends a plurality of data linking blocks, including three run-out blocks, to each unit of data going to be continuously written to the optical disc, and the error-correction coding means interleaves the data with a unit delay of seven frames.
In the above data recording apparatus, when the optical disc discriminator has judged that the data is going to be written to the conventional standardized optical disc, the data linking block appending means appends a plurality of data linking blocks, including two run-out blocks, to each unit of data going to be continuously to be written to the optical disc. Then, the error-correction coding means interleaves the data having the data linking blocks appended thereto with a unit delay of four frames. Further, the data interleaved with the unit delay of four frames is written by the data writing means to the conventional standardized optical disc.
Also, in the data recording apparatus, when the optical disc discriminator has judged that the data is going to be written to the optical disc having the higher recording density than the conventional standardized optical disc, the data linking block appending means appends a plurality of data linking blocks, including three run-out blocks, to each unit of data going to be continuously to be written to the optical disc. Then, the error correction coding means interleaves the data having the data linking blocks appended thereto with a unit delay of seven frames. Further, the data interleaved with the unit delay of seven frames is written by the data writing means to the conventional standardized optical disc.
As in the above, in the data recording apparatus, since data linking block appending and error-correction coding are effected in one or other manner, depending upon the recording density of an optical disc to which data is going to be written, data can properly be linked even in the optical disc having the high recording density while preventing the ability of correcting a burst error from being lower, and the error correction and data linking can properly be done in the conventional optical disc as well.
Also the above object can be attained by providing a data recording method for recording data to a conventional standardized optical disc as well as to an optical disc having a higher recording density than the former optical disc, the method including according to the present invention:
a first step at which it is judged to which the data is going to be written, the conventional standardized optical disc or the optical disc having a higher recording density than the former optical disc;
a second step at which a plurality of data linking blocks is appended to each unit of data going to be continuously written to the optical disc;
a third step at which error-correction coding, including interleaving, is made of the data having the data linking blocks appended thereto; and
a fourth step at which the data having been subjected to the error-correction coding at the third step is continuously written to the optical disc at each unit of data having the plurality of data linking bocks appended thereto at the second step.
In the above data recording method according to the present invention, when it has been judged at the first step that data is going to be written to the conventional standardized optical disc, a plurality of data linking blocks, including two run-out blocks, is appended at the second step to each unit of data going to be continuously written to the optical disc, and the data is interleaved with a unit delay of four frames at the third step. When it has been judged at the first step that data is going to be written to the optical disc having the higher recording density than the conventional standardized optical disc, a plurality of data linking blocks, including three run-out blocks, is appended at the second step to each unit of data going to be continuously written to the optical disc, and the data is interleaved with a unit delay of seven frames at the third step.
In the above data recording method, since data linking block appending and error-correction coding can properly be effected correspondingly to the recording density of an optical disc to which the data is going to be written, data can properly be linked even in the optical disc having the higher recording density while preventing the ability of correcting a burst error from being lower, and the error correction and data linking can properly be done in the conventional optical disc as well.
Also, the above object can be attained by providing a data playback apparatus for reading data from a first optical disc defined under a first standard as well as from a second optical disc defined under a second standard, the apparatus including according to the present invention:
an optical head which emits a laser light to the optical disc and detects a reflected light from the optical disc;
an optical disc discriminator for judging from which the data has been read by the optical head, the first optical disc or second optical disc;
means for error correction, including de-interleaving, of the data having been read by the optical head; and
means which is supplied with the data whose error has been corrected by the error correcting means and removes a plurality of data linking blocks having been appended, for data linking, to each unit of the data having continuously been written to the first and second optical disc.
In the above data playback apparatus, when the optical disc discriminator has judged that the data has been read by the optical head from the first optical disc, the data linking block removing means removes the plurality of data linking blocks, including two run-out blocks, from each unit of data having continuously been written to the optical disc. When the optical disc discriminator has judged that data has been read from the second optical disc, the data linking block removing means removes the plurality of data linking blocks, including three run-out blocks, from each unit of data having continuously been written to the optical disc.
Also in the data playback apparatus, when the optical disc discriminator has judged that data has been read by the optical head from the first optical disc, the error correcting means interleaves the data having been read by the optical head with a first unit delay.
When the optical disc discriminator has judged that the data has been read by the optical head from the second optical disc, the error correcting means interleaves the data having been read by the optical head with a second unit delay larger than the first unit delay.
In the above data playback method, since data linking block appending and error-correction coding are effected in one or other manner, depending upon the recording density of an optical disc from which data is going to be read so that such processes can properly be effected correspondingly to the recording density of an optical disc from which the data is going to be read, the data can properly be read from the optical disc having the higher recording density while preventing the ability of correcting a burst error from being lower, and the data can properly be read from the conventional optical disc as well.
Also the above object can be attained by providing a data playback method for reading data from a first optical disc defined under a first standard as well as from a second optical disc defined under a second standard, the method including according to the present invention:
a first step at which a light beam is emitted to the optical disc and a return light from the optical disc is detected;
a second step at which it is judged to which the light beam has been emitted, the first optical disc or second optical disc;
a third step at which error correction, including de-interleaving, is made of the data having been read from the optical disc; and
a fourth step at which there is removed a plurality of data linking blocks having been appended, for data linking, at each unit of the data whose error has been corrected at the third step and which have continuously been written to the optical disc.
In the above data playback method, when it has been judged at the second step that the data is going to be read from the first optical disc, the data is interleaved with a first unit delay at the third step.
When it has been judged at the second step that the data is going to be read from the second optical disc, the data is de-interleaved at the third step with a second unit delay larger than the first unit delay.
In the above data playback method, since the data linking block appending and error correction can properly be effected correspondingly to the recording density of an optical disc from which the data has been read, the data can properly be read from the second optical disc having the high recording density while preventing the ability of correcting a burst error c from being lower, and the data can properly be read from the first optical disc as well.
Also the above object can be attained by providing an optical disc having data recorded therein by method for recording data to a conventional standardized optical disc or to an optical disc having a higher recording density, the method including according to the present invention:
a first step at which it is judged to which the data is going to be written, the conventional standardized optical disc or the optical disc having a higher recording density than the former optical disc;
a second step at which a plurality of data linking blocks is appended to each unit of data going to be continuously written to the optical disc;
a third step at which error-correction coding, including interleaving, is made of each unit of data having the data linking blocks appended thereto; and
a fourth step at which the data having been subjected to the error-correction coding at the third step is continuously written to the optical disc at each unit of data having the plurality of data linking bocks appended thereto at the second step; and
when it having been judged at the first step that data is going to be written to the conventional standardized optical disc, a plurality of data linking blocks, including two run-out blocks, being appended at the second step to each unit of data going to be continuously written to the optical disc and the data having the data linking blocks appended thereto is interleaved with a unit delay of four frames at the third step.
In the above optical disc, when it has been judged at the first step that data is going to be written to the optical disc having the higher recording density than the conventional standardized optical disc, a plurality of data linking blocks, including three run-out blocks, is appended, at the second step, to each unit of the data going to be continuously written to the optical disc and the data having the data linking blocks appended thereto is interleaved with a unit delay of seven frames at the third step.
Also in this optical disc, since the data linking block appending and error-correction coding processes are properly effected correspondingly to the recording density of the optical disc to which data is going to be written, data can properly be written to, and read from, even the optical disc having the high recording density while preventing the ability of correcting a burst error from being lower, and the data can properly be written to, and read from, the conventional standardized optical disc as well.
Also, in the above optical disc according to the present invention, a plurality of data linking blocks, including three run-out blocks, is appended to each unit of data going to be continuously written to the optical disc, the data having the data linking blocks thus appended thereto is subjected to error-correction coding including interleaving with a unit delay of seven frames, and the data having thus been subjected to the error-correction coding is continuously recorded to the optical disc at each unit of data block having the plurality of data linking blocks appended thereto.
In the above optical disc, since the data linking block appending and error-correction cording processes are properly effected correspondingly to the recording density of an optical disc to which data is going to be written, the data can properly be written to, and read from, the optical disc having the higher recording density, as well, while preventing the ability of correcting a burst error from being lower.
These objects and other objects, features and advantages of the present intention will become more apparent from the following detailed description of the preferred embodiments of the present invention of an optical disc drive which writes and/or reads data to and/or from a CD-R (recordable optical disc) when taken in conjunction with the accompanying drawings.